Liquid-cooled single or multiple cylinder two-cycle combustion engine

ABSTRACT

Liquid-cooled single or multiple cycle two-cycle internal combustion engine produced by mold or die casting, particularly pressure-casting, having a cylinder liner with apertures to the waste gas and transfer port channels, as well as a piston controlling the changes in the load where conically tapering channels are formed in the cylinder block outside the cylinder liner parallel, or nearly parallel, to the longitudinal axis of the cylinder where the lower channel portion forms the transfer port channel and the upper channel portion the cooling water chamber, and both channel portions are tightly sealed relative to one another by an insert member in the area of the passage from the transfer port channel to the combustion chamber of the cylinder.

United States tgt Strossner et a1.

LIQUID-COOLED SINGLE OR MULTIPLE CYLINDER TWO-CYCLE COMBUSTION ENGINE Inventors: Johannes ii Numberg; Armin Drebes, Grosshelfendorf, both of Germany Fix-ma Zundapp-Werke Gesellschatt mit beschrankter l-laitung, Munchen, Germany Filed: Oct. 30, 1970 Appl. No.: 85,374

Assignee:

Foreign Application Priority Data Nov. 5, 1969 Germany ..P 19 55 586.3

US. Cl ..123/4l.72, 123/73 A, 123/74 A, 123/193 C Int. Cl ..F02f l/l0, F02b 33/04 Field of Search ..l23/73 R, 73 A, 74 R, 74 A, 123/74 B, 65 R, 65 PD, 65 W, 65 P, 41.72, 41.78, 41.79, 41.8,193 C, 193 C? References Cited UNITED STATES PATENTS 6/1914 wooleryu......... .,...,....iQ 23/Z3 Au);

1,194,830 8/1916 Fay..'. ..l23/41.78 2,102,041 12/1937 Spelts ..l23/65 R X 2,560,700 7/1951 Pervier ...l23/41.72 X 2,627,255 2/1953 Kiekhaefer ..l23/73 A X FOREIGN PATENTS OR APPLICATIONS 525,823 9/l940 Great Britain ..l23/65 1 Primary Examiner-Al Lawrence Smith Attorney-Robert H. Jacob [57] ABSTRACT Liquid-cooled single or multiple cycle two-cycle internal combustion engine produced by mold or die casting, particularly pressure-casting, having a cylinder liner with apertures to the waste gas and transfer port channels, as well as a piston controlling the changes in the load where conically tapering channels are formed in the cylinder block outside the cylinder liner parallel, or nearly parallel, to the longitudinal axis of the cylinder where the lower channel portion forms the transfer port channel and the upper channel portion the cooling water chamber, and both channel portions are tightly sealed relative to one another by an insert member in the area of the passage from the transfer port channel to the combustion chamber of the cylinder.

11 Claims, 11 Drawing Figures PAIENTEDFEBM m2 3,643,637

SHEEI 1 OF 4 Fig. 1

IN V EN TORS LIQUlD-COOLED SINGLE R MULTIPLE CYLINDER TWO-CYCLE COMBUSTION ENGINE BACKGROUND OF THE INVENTION The invention relates to a liquid-cooled single or multiple cylinder two-cycle internal combustion engine produced by the mold or die casting, preferably pressure-casting method with cylinder liners having passage apertures to the exhaust and the transfer port channels with a working piston controlling the load changes.

For reasons of weight and cost in the production of cylinders for two-cycle internal combustion engines, the pressurecasting method is generally preferred which includes the conventional hard chrome plating of the cylinder liner. While in the mold-casting method cores are placed in the casting mold produced usually by the Croning method in order to form the transfer channels where the cores have to be newly produced for each cylinder, steel cores that can be repeatedly inserted are utilized in the pressure-casting method in order to form the transfer channels. For this purpose the channel part of the transfer port channels that is disposed parallel to the longitudinal axis of the cylinders is formed by a first core drawn from the foot of the cylinder simultaneously with the cylinder core. The second core however which is formed as a hook core produces the channel portion which constitutes the connection between the transfer port channel and the internal space of the cylinder.

However, this method of production is only applicable to combustion engines where the cylinder is threadedly secured to the crank housing or is releasably secured thereto in some other fashion. As compared to this, internal combustion engines where the cylinders are formed as a unitary structure with the crank housing are preferably cast, cannot be made in the aforementioned manner. For these last-mentioned internal combustion engines which are particularly multiple-cylinder engines the construction and forming of the transfer port channels from the foot end of the cylinder is not possible because of the housing walls and of the hubs for the crankshaft bearings that are disposed in front thereof. Therefore, attempts have already been made in the practice to overcome these difficulties with combustion engines where the cylinders are cast as a unit with the crank housing, in that a prefabricated cylinder liner of cast iron or steel which is formed with transfer port channels that are open toward the inner space of the cylinder, or the combustion chamber, have the casting formed around them by the mold-casting method from the outside, or by the pressure-casting method. This method of construction has the disadvantage, however, that on the one hand difficulties are caused between the open channels and the piston, and on the other hand the connection of the cylinder liners with the applied hull of light metal (aluminum) can only be obtained under difficulties and at great expense. Since in addition several expensive operations are required for making an internal combustion engine in that manner, this type of construction is time-consuming and expensive.

In a further possible embodiment also frequently used which can be applied only to single-cylinder combustion engines, the transfer ports are formed from the outside. In this connection, the channels that thus are open toward the outside are closed by application of suitable sheet metal plates or cast portions. Also this form of construction has the shortcomings that it is cumbersome and expensive and requires additional assembly work for the mounting of the closure bodies.

SUMMARY OF THE lNVENTlON In accordance with the invention, an internal combustion engine is to be provided of the type referred to above which can be produced in a simple manner and economically, and which besides being suitable for the mold-casting method is in a particular manner also suitable for the pressure-casting method.

In accordance with the invention, this is achieved in that continuous, slightly conical tapering channels are provided that extend externally of the cylinder liners from the top of the cylinder parallel, or substantially parallel, to the longitudinal axis of the cylinder are formed in the cylinder block, where the lower channel portion defines the transfer port channel and the upper portion defines the cooling water space and both channel portions are separated or sealed relative to one another by an insert body in the area of the passage from the transfer port channel to the combustion chamber of the cylinder.

This form of construction of internal combustion engines that is suitable for the mold or die casting method, and particularly for the pressure-casting method can be carried out without jkonsiderable technical effort and provides the advantage 'that it is applicable without difficulty to single and multiple cylinder. internal combustion engines. In addition, a simple and economical solution is provided especially for internal combustion engines where the cylinder or cylinders and the crank housing are a unitary structure, preferably cast, which contributes to the simplification and time saving in the assembly of internal combustion engines and eliminates density or sealing problems in the gaps between cylinder and crank housing. From a manufacturing standpoint, this form of construction provides the advantage that the cores which longitudinally taper conically in accordance with the channel shapes that may be made, for example of steel, can always be reused at any time, which has a particularly advantageous effect on the cost. Furthermore, by means of this construction of the transfer port channels, a cooling water space is simultaneously provided which is disposed above the transfer port channels and is spacially and tightly separated by suitable plugs.

In accordance with a further modification of the invention, the insert bodies or plugs may in their longitudinal extent be in the form of conically tapering plugs which, on the one hand, end at the level of the cylinder top and on the other hand are flush with and close the upper edge of the passage apertures in the cylinder liner and have at their ends facing the transfer port channels a somewhat concavely arcuate shape that favors the flow. By means of these closure plugs that are simple to construct, a safe and tight termination of the upper part of the transfer port channels is provided in a simple manner. The conical shape and the fitting of the plug is preferably chosen in a manner that the plug can be partly introduced by hand into the channel and then projects above the surface of the cylinder top. Only by placing the cylinder cover and subsequently threadedly securing the same, the plug is fully pressed into the channel. The end of the plug which closes the transfer port channel presents a slightly concave arcuated surface whereby guiding of the combustible substances by way of the transfer port channels to the interior of the cylinder is obtained in a manner that favors the flow.

In accordance with a further modification of the invention, the plugs may be provided with an aperture forming a pocket that extends down from the top of the cylinder. Thus, a cooling water space is provided in a simple and economical manner above the transfer port channels which due to its particular construction in the form of a dead end bore completely prevents direct penetration of the coolant liquid into the transfer port channels without being especially sealed for this purpose. On the other hand, this form of construction affords the advantage of saving material and, therefore, also weight Furthermore, the plugs may present small projections that extend along their outer surface longitudinally that may in accordance with a further modification of the invention engage correspondingly formed grooves on the inner walls of the upper channel portion that constitutes the cooling water space. These two structural embodiments provide for still firmer and tighter fitting of the plug in the upper channel part which fully justifies the minor additional expense for the production thereof. In order to keep the additional expense as small as possible, it is sufficient, however, to merely provide the plug with small projections which when the plug is forced in, penetrate into or bend over in the upper smooth wall channel portion and thus insureof tight seating.

In accordance with a further development of the invention, the transfer port channels formed in the lower channel area may have at their upper transfer port apertures proximate the combustion space of the cylinder a bore that extends transversely of the axis of the cylinder which sealingly receives an insert member in the form of a plug, which at its circumferential surface that closes the lower channel portions with respect to the upper channel portions possesses a recess, the cross section of which is adapted to the upper contour of the transfer port aperture that has a slightly arcuated base favoring the flow. This construction provides the advantage that the upper channel portion that serves for receiving the cooling water is maintained at its complete cross-sectional size and results in more favorable cooling of the cylinder spaces due to the greater cooling water capacity. Since the receiving bores for the plugs can be made simultaneously as the entire cylinder block is cast and need not be processed, the entire production becomes relatively simple and economical. Also, the plugs proper can largely remain unprocessed, except for the recesses that are formed to favor the flow. For maximum output motors, it is suitable, however, to machine the plugs, as well as the receiving bores which is possible in a simple manner and without considerable expense due to the favorable circular cross-sectional construction of the plugs and of the receiving bores. Since furthermore the plugs are of circular cross section, the production thereof and fitting them into the bores is still simpler.

In a further development of this construction, the plugs may be provided at least at their front ends with a groove that extends transversely of their longitudinal axis. This provides the advantage that the plug when it is pressed into the bore by means of a suitable tool, can be brought securely and simply exactly into the required position.

Furthermore, the outer ends of the plugs may be provided on both sides with dead end bores imparted from the outside. This results in a material and weight economy which advantageously affects the entire internal combustion engine.

In a further development in accordance with the invention, the upper channel part that constitutes the cooling water space may have a greater expansion of the cross section of the channels that are on opposite sides of each cylinder in the direction transversely of the axis connecting the center lines of the cylinder. For this purpose, it is possible to seat on the flanged surfaces thus formed an insert element in the form of a plug having a collar and presenting a surface facing the lower channel portions that advantageously affects the flow, and this plug can be connected tightly and firmly by means of screws or other connecting elements with the flanged surfaces.

Also in this embodiment, the upper channel part that constitutes the cooling water space is maintained at its full crosssectional size because the plugs can be in the form of flat disks having short cylindrical projections. The production of the individual channel portions in the casting method, as well as also the production of the plugs, is simple and involves only minor expenses. Since the plugs are held in place by screws, they remain safely and tightly in the predetermined position for any condition of operation.

A groove extending around these plugs at the outer circumference serves to receive a sealing ring which results in minor increases in cost for this embodiment, but which is of little consequence as compared to the better sealing effect thus obtained. The sealing ring in this event, together with the type and form of plug, also affords the advantage that material expansions of the cylinders caused by heat can be absorbed without harm and without affecting the tightness of the seal. The grooves for receiving the sealing rings may be provided on the cylindrical part, as well as also around the collar of the plugs.

BRIEF DESCRIPTION OF THE DRAWINGS Further features and advantages of the invention will become apparent from the embodiments illustrated in the drawings in which:

FIG. 1 is a section through a one-cylinder internal combustion engine provided with the channels formed in accordance with the invention,

FIG. 2 is a section through the one cylinder taken along line II-II of the combustion engine in accordance with FIG. 1,

FIG. 3 is a section through a one-cylinder combustion engine having circular plugs in the channels,

FIG. 4 is a section taken along line IVIV in accordance with F IG. 3,

F IG. 5 is a longitudinal section through a two-cylinder combustion engine,

FIG. 6 shows in perspective a circular plug in accordance with FIGS. 4 and 5,

FIG. 7 shows a circular plug in accordance with FIG. 6 in longitudinal section,

FIG. 8 is a longitudinal section through a multiple-cylinder combustion engine having different insert members in the channels,

FIG. 9 is a section through a multiple-cylinder combustion engine in accordance with FIG. 8 taken along line IX-IX,

FIG. 10 is a section of a plug for a combustion engine in accordance with FIGS. 8 and 9, and

FIG. 11 shows a different plug in section for a combustion enginein accordance with FIGS. 8 and 9.

DESCRIPTION OF THE INVENTION FIGS. 1 and 2 illustrate a single-cylinder combustion engine where the cylinder 1 and the crank housing 2 are cast in the form of a unitary structure. In this unit the cylinder 1 has formed on it two channels 4 that extend from the end 3 for the cylinder cover and are displaced by about relative to one another. These channels 4 extend parallel to the longitudinal axis of the cylinder 5 and terminate above the crank housing 2 in the manner of dead end bores. The inner walls 6 of the channels are slightly inwardly inclined from the cover end 3, so that, beginning at the cylinder cover end 3, there results a continually narrowing cross section of the channels 4. Approximately at the level of the bottom 7 of the channels, apertures 9 are provided in the wall 8 of the cylinder chamber which provide the connection between the interior of the crank housing and the channels 4. Aligned apertures 10 are disposed in the wall of the cylinder chamber 8 at some distance above the apertures 9, by way of which the channels 4 are in communication with the combustion chamber 11 of the cylinder 1. The lower channel portion 12 between the apertures 9 and 10 constitutes the transfer port channel. The transfer port channels are tightly closed proximate the cover end 3 by inserts in the form of plugs 13. These plugs taper conically along their longitudinal extent generally in the same manner as channels 4. In order to provide for better guidance and securing, the plugs 13 are provided with small longitudinally extending projections or beads 14 which in accordance with FIGS. 1 and 2 engage grooves 15 on the inner walls of the upper channel portions 30. Grooves 15 are not absolutely necessary, In various embodiments it is sufficient to provide the plugs 13 with small sharp edged projections 14 and press them into the smooth walls of the upper channel portions 30. In addition, the plugs 13 have a formed dead end opening 16 that serves to accommodate cooling fluid. At the end 17 of the plugs 13 which faces the channel portion 12 they are provided with slightly concave curvature, while the contour 18 of the end 17 extending toward the cylinder chamber wall 8 is in the assembled condition in alignment with the upper edge of the aperture 10. The entire gas exchange is controlled by the piston 20 in the cylinder chamber 8 in cooperation with apertures 9 and 10. I

In FIGS. 3 and 4 a one-cylinder internal combustion engine of generally the same form of construction is illustrated as that in accordance with FIGS. 1 and 2. Also here the channels 4 are formed from the cover end 3 of the cylinder and extend parallel to the axis 5 of the cylinder with the cross-sectional area tapering down continually. In the area of the upper passage apertures 10, passage bores 21 are provided in the channels 4 transversely of the longitudinal axis 5 of the cylinder, the center of which is somewhat above the upper edge 19 of the apertures 10. Plugs 22 of circular shape are tightly seated in these bores 21 with a recess 23 along their circumference that is disposed transversely with respect to their longitudinal axis. The base 24 of this recess 23 is of slightly arcuate shape and when the plug 22 is mounted it is aligned with the upper edge 19 of the through passages 10. In order to reduce the weight of the plugs 22, both ends 25 and 26 are provided with dead end bores 27 and 28 (see FIGS. 6 and 7). At one of the ends 27 or 28 the plugs 22 are also provided with a groove 29 that extends transversely of the longitudinal axis. [t is possible by means of a tool engaging the groove 29 to align the plug 22 as it is pressed in securely in the prescribed position in the bore 21, so that the recess 23 is located in the aforementioned position relative to the flow channel.

In FIG. 5 a two-cylinder internal combustion engine is illustrated which is equipped with such plugs 22. It can be seen that the two cylinders l are disposed relatively closely to one another. This arrangement makes it possible to make multiplecylinder engines which occupy only a small space, which in turn is advantageous for the total weight.

A further embodiment of a multiple-cylinder combustion engine having channels 4 formed inwardly from the cover end 3 is shown in FIGS. 8 and 9. Also here the channels 4 are disposed parallel to the longitudinal axis 5 of the cylinder and taper down conically from the cylinder cover end 3. Here the upper channel portions 30 which form spaces for the cooling water have a greater cross-sectional expansion transversely of the connecting axis or line of the channels 4 that are opposite each other for each cylinder than the lower channel portions 12 which serve as overflow channels. This means that the inner walls 31 of the upper channel portion are displaced further outwardly than what corresponds to the normal cross sections of channels 4, while when taking into account the conical taper, the inner walls 32 correspond to the normal cross section of the channels 4. In this manner there are formed oppositely disposed sections or flange surfaces 33 approximately at the level of the upper passage openings. A plug 34 is nowplaced into the upper channel portion 30 which has a collar 35 that expands only in this plane, while the collar 35 in the other plane is equal in cross section to the cylindrical plug portion 36. The plug 34 rests with the expanded collar portions 35 upon the flange surfaces 33 of the upper channel portion 30 and is connected there securely and tightly with the flange surfaces 33 by means of stud screws 37. In a groove 38, 39 which may be provided either on the cylindrical part of the plug 34 or on its collar a seal 40 is inserted. The end wall 41 of the plug 34 which faces the overflow channel is also of a slightly arcuate shape that favors the flow and is in alignment with the upper edge of the passage aperture 10.

Having now described our invention with reference to the embodiments illustrated, what we desire to protect by letters patent is set forth in the appended claims.

We claim:

1. In a liquid-cooled single or multiple-cylinder two-cycle internal combustion engine produced by a mold-casting, particularly pressure-casting method, a cylinder block having a cylinder provided with upper and lower apertures to waste gas and transfer port channels and a piston for controlling changes in the engine load, conically tapering channels extending in said cylinder block from the cover end of the cylinder substantially parallel to the axis of the cylinder, said channels having a lower portion defining a transfer port channel and an upper portion defining a cooling water space, and an insert member intermediate said lower and said upper channel portions and proximate said upper aperture of the transfer port to the combustion chamber tightly sealing said transfer port relative to said cooling water space. i

2. lntemal combustion engine in accordance with claim 1',

where said insert bodies are defined by plugs tapering conically in longitudinal direction, said plugs terminating at one end at the level of the top of the cylinder and at the other end flush with the upper edge of said transfer port, said other end presenting a concave surface proximate the upper edge of said upper transfer port aperture.

3. Internal combustion engine in accordance with claim 2, where said plugs are provided with dead end bores extending inwardly from the top of the cylinder.

4. lntemal combustion engine in accordance with claim 2 where said plugs are provided with small projections disposed on the outer surface thereof longitudinally of said plugs.

5. internal combustion engine in accordance with claim 4, where said upper portions of said channels are provided with axially extending grooves for engagement with said projections on said plugs.

6. Internal combustion engine in accordance with claim 1. including transverse passages proximate said lower portions of said channels proximate said upper apertures of the cylinder liner, a plug seated in each said aperture sealing said lower channel portion relative to the upper channel portion and having a recess defining an arcuately shaped flow-conducting surface in alignment with said upper aperture.

7. Internal combustion engine in accordance with claim 6, where said plugs are of generally cylindrical shape.

8. Internal combustion engine in accordance with claim 6. where said plugs are provided at one end with a groove extending transversely of the longitudinal axis of the plug.

9. lntemal combustion engine in accordance with claim 8. including dead end bores extending inwardly from the outer ends of the plugs.

10. lntemal combustion engine in accordance with claim I, where the cross-sectional dimensions of said upper portions of said channels are greater transversely of the axis connecting said channels than that of the lower portions, thereby providing surfaces defining flanged ledges, and said insert member is a plug having a collar portion, one each sealingly seated on each flanged ledge and having an arcuately shaped end surface proximate said lower channel portion.

11. lntemal combustion engine in accordance with claim 10, where a circumferential annular groove extends around said plugs and a sealing ring is disposed in each said groove.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 57 Dated February 22, 1972- Inventor(s) Johannes StrkSssner and Armin Drebes It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 1, line 5 after "cylinder" insert -1iner Signed and sealed this 13th day of June 1972.

LSEAL) ttest:

DWARD M.FLETCHER, JR. ROBERT GOTTSCHALK ttesting Officer Commissioner of Patents FORM PC4050 (0459) USCOMM-DC suave-ps9 .5. GOVERNMENT PFUNTlNG DFFICE I 969 365-334 

1. In a liquid-cooled single or multiple-cylinder two-cycle internal combustion engine produced by a mold-casting, particularly pressure-casting method, a cylinder block having a cylinder provided with upper and lower apertures to waste gas and transfer port channels and a piston for controlling changes in the engine load, conically tapering channels extending in said cylinder block from the cover end of the cylinder substantially parallel to the axis of the cylinder, said channels having a lower portion defining a transfer port channel and an upper portion defining a cooling water space, and an insert member intermediate said lower and said upper channel portions and proximate said upper aperture of the transfer port to the combustion chamber tightly sealing said transfer port relative to said cooling water space.
 2. Internal combustion engine in accordance with claim 1, where said insert bodies are defined by plugs tapering conically in longitudinal direction, said plugs terminating at one end at the level of the top of the cylinder and at the other end flush with the upper edge of said transfer port, said other end presenting a concave surface proximate the upper edge of said upper transfer port aperture.
 3. Internal combustion engine in accordance with claim 2, where said plugs are provided with dead end bores extending inwardly from the top of the cylinder.
 4. Internal combustion engine in accordance with claim 2 where said plugs are provided with small projections disposed on the outer surface thereof longitudinally of said plugs.
 5. Internal combustion engine in accordance with claim 4, where said upper portions of said channels are provided with axially extending grooves for engagement with said projections on said plugs.
 6. Internal combustion engine in accordance with claim 1, including transverse passages proximate said lower portions of said channels proximate said upper apertures of the cylinder liner, a plug seated in each said aperture sealing said lower channel portion relative to the upper channel portion and having a recess defining an arcuately shaped flow-conducting surface in alignment with said upper aperture.
 7. Internal combustion engine in accordance with claim 6, where said plugs are of generally cylindrical shape.
 8. Internal combustion engine in accordance with claim 6, where said plugs are provided at one end with a groove extending transversely of the longitudinal axis of the plug.
 9. Internal combustion engine in accordance with claim 8, including dead end bores extending inwardly from the outer ends of the plugs.
 10. Internal combustion Engine in accordance with claim 1, where the cross-sectional dimensions of said upper portions of said channels are greater transversely of the axis connecting said channels than that of the lower portions, thereby providing surfaces defining flanged ledges, and said insert member is a plug having a collar portion, one each sealingly seated on each flanged ledge and having an arcuately shaped end surface proximate said lower channel portion.
 11. Internal combustion engine in accordance with claim 10, where a circumferential annular groove extends around said plugs and a sealing ring is disposed in each said groove. 